1852.) 73 
Conspectus Crustaceorum, Sc. Conspectus of the Crustacea of the Exploring 
Expedition under Capt. Wilkes, U. S. N., including the Crustacea Can- 
crorpEA CorystorpEa. By James D. Dana. 
I. CRUSTACEA CANCROIDEA. 
A synopsis of the genera of Cancroidea—the Cyclometopa of Edwards—in- 
cluding their arrangement into families and other groups, has been published by the 
writer in the American Journal of Science, 2d ser., vol. xii, p. 121. The follow- 
ing pages contain descriptions of the new species in the Expedition collections, 
arranged in accordance with the classification explained in that paper. The 
distinctive characters of the genera will there be found, both of those of other 
authors, as far as accepted, and those here instituted. 
Fam. I. CANCRID A. 
Subfam. CANCRIN AL. 
Genus Cancer, Leach, (Platycarcinus, Ldw.) 
CaNCER MAGISTER.—Carapax nudus, granulatus, paulo convexus, superficie 
paulo undulatus, lateraliter triangulatus et acutus, margine postero-laterali fere 
recto, antero-laterali 10-dentato, dentibus paululo prominentibus, margine 
dentis postero longissimo et fere recto, subtiliter crenulato, dente ultimo 
triangulato; fronte inter-antennali 3-dentato; articulo antennarum externarum 
lmo apicem crassé producto. Pedes antici subequi, manu supra cristata, multi- 
dentata, extus costata, digito mobili supra denticulato. Pedes 8 postici valde 
compressi, tarso paulo lato, articulis supra granulatis, 4to supra canaliculato, 
tarso articuloque 5to pedis 5ti infra bene ciliatis. Articulus maxillipedis externi 
3tius oblongus, apice externo obliqué truncatus. Has. portu-“¢ San Francisco.’ 
Long. carapacis 43”, lat. 7’. 
Cancer GRaciLis.—Carapax nudus, partim minute granulatus, valde convexus, 
non distincté areolatus, superficie non undulatus, lateraliter triangulatus et 
acutus, margine postero-laterali fere recto, antero-laterali 9-dentato, dentibus 
regularibus, acutis, paulo prominentibus, dente 1mo vix longiore quam 2dus, 
totis margine postero fere rectis et longis et subtiliter denticulatis, fronte inter- 
antennali 3-dentato. Maxillipedes externi pubescentes, articulo 3tio apicem 
externum valde arcuato aut rotundato, margines apicalem et externum longé 
ciliato. Pedes antici subequi, manu subcristata, crista 1—2-dentata, superficie 
externa costata. 'Pedes 8 postici nudi, tarso longo, tenuissimo, nudo. fab. 
portu “San Francisco.” Long. carapacis 13’, lat. 19’”. 
Subfam. XANTHIN A. 
Genus Liomera, Dana. 
Carpilio, aspectu, pedibus nudis quoad margines obtusis antennisque similis. 
Carapax valde transversus, subellipticus, lateribus rotundatis, margine antero- 
laterali non breviore quam postero-lateralis, fronte brevissimé bilobato. Ramus 
maxillipedis primi internus non lobatus, apice fere rectus. Pedes usque ad 
tarsos nudi. An Carpilius cinctimanus, White, hic pertinet ? 
Liomera wATA.—Carapax nitidus, valde transversus, transversim bene 
ellipticus, antice versus marginem anticum subareolatus, in medio areolis in- 
conspicuis ; fronte brevi, perpendiculariter deflexo, superné viso fere recto et 
super orbitas vix saliente, leviter emarginato; margine antero-laterali crasso et 
erassé rotundato, 4-lobato, lobis 2do 3tio 4toque validis, rotundatis, 3tio majore. 
Pedes antici equi, mediocres, manu levi, digitis brevibus. Had. ad insulas 
‘Peejee.””? Long. carapacis 7’, lat. 132’. 
Genus Actaa, (DeHaan) Dana. 
Actma AREOLATA.—A. hirtissimo vel specioso affinis. Carapax latior, valde 
transversus, infra omnino brevissimé hirsutus, supra omnino areolatus, sub- 
